Category Archives: theropods

Cincinnati’s Union Terminal is an incredible building. This colossal art deco structure is a sight to behold inside and out, and the muraled semi-dome in its central rotunda is among the largest of its kind in the world. Built in 1933 as a train station (and functioning as one today, after a mid-century hiatus), Union Terminal is also home to the Cincinnati Museum Center (CMC), which relocated here from a downtown location in the early 1990s.

I visited CMC once before in 2013, to see the traveling Ultimate Dinosaurs exhibit. I also saw the permanent natural history exhibits that were in place at the time, which included some very elaborate walk-through reconstructions of a Pleistocene forest and a modern cave. These exhibits were constructed in the 90s, and had a lot of the hallmarks of museum design in that era. For example, the ice age galleries were framed around visitors “examining evidence like scientists,” which in practice involved binary question-and-answer stations and interactives where the action performed didn’t really connect with the concept meant to be communicated. Nevertheless, the actual fossil collection on display—mostly from Big Bone Lick in Kentucky—was impressive, as were the ambitious, large-scale dioramas.

The 1990s-era ice age gallery.

This huge diorama featured life-sized wolves, a ground sloth, and a mastodon mired in mud.

Since then, Union Terminal and CMC have undergone a sweeping transformation. In 2014, the National Trust named the building—which had never been completely renovated in its 80 year history—one of the country’s most endangered historic places. Happily, the county took action, and raised funds to restore and modernize Union Terminal. In the process, most of the existing museum galleries were completely demolished, and the spaces they occupied were restored to match the building’s original architecture.

This strikes me as a bold move. Typically, legacy museums will gradually update or replace old exhibits as funding allows. In contrast, the CMC renovation started with a total teardown, and new exhibits are now being added in phases. As of this writing, the natural history and science side of the building includes a brand-new dinosaur gallery (discussed here), the aforementioned walk-through cave, a partial exhibit on the moon landing, and an assortment of temporary-looking exhibits. A new ice age gallery, the rest of the space exhibit, and immersive exhibits about Cincinnati history are slated to open later this year, and it appears fundraising is underway for future projects, including a Paleozoic fossil hall.

The hall’s only ornithischian Othnielosaurus follows in the footsteps of Galaemopus and Diplodocus.

To cut to the chase, the dinosaur hall is excellent. Developed by senior project manager Sarah Lima and curator Glenn Storrs, this is effectively a brand-new exhibit, since the old dinosaur gallery was quite limited. When the original CMC exhibits were built, the strengths of the vertebrate paleontology collections were primarily in Quaternary mammals and Paleozoic invertebrates. Over the last 20 years, however, the museum has been focused on the Jurassic. In particular, regular field work at the Mother’s Day Quarry in Montana has yielded a trove of Jurassic fossils, including some very unique sauropod specimens. The gallery includes an 80% complete Galaemopus, a composite juvenile Diplodocus, sauropod skin impressions, and a one-of-a-kind juvenile Diplodocus skull. In spite of the unspoken adage, the Morrison fauna is not resolved, and new secrets of this ecosystem are still being recovered.

Torvosaurus towers over a composite Allosaurus assembled from Cleveland-Lloyd fossils.

Other key specimens in the new exhibit were purchased from commercial fossil collectors. Jason Cooper, a Cincinnati native, discovered the Torvosaurus, which is the only real specimen of its kind on display anywhere. Along with his father Dan and brother Ben, Cooper excavated the 50% complete skeleton from a private Colorado ranch and prepared and mounted it for display. The museum purchased the Daspletosaurus from the Rocky Mountain Dinosaur Research Center. Anthony Maltese and colleagues excavated the skeleton in 2006 and prepared it over the course of several years.

Nicknamed “Pete III,” the Daspletosaurus shares its platform with two Dromaeosaurus casts and a cast skull of the Nation’s T. rex.

Like many newer fossil exhibits, the gallery is well-lit and spacious. The art deco design of Union Terminal informs the look of the hall: large windows fill the space with natural light, and the larger specimens are arranged on minimalist platforms that can be viewed from many angles, including from above. I found it noteworthy how close visitors can get to the mounted skeletons. Although the platforms are fairly high up, there are no glass barriers. I found that I could get within a few inches of the Galaemopus feet without much effort. I’m sure a slightly taller or more determined person could manage to touch the fossils.

Hopefully, they’ll be distracted by the many exhibit elements that are meant to be touched. In contrast to the 1990s exhibits, CMC has mostly done away with physical interactives, instead emphasizing touchable models and digital touchscreens. One particularly impressive inclusion are the digital video cameras (in robust cylindrical housing) connected to large monitors. Visitors can use these to get real-time magnified views of certain fossils, including a chunk of Tyrannosaurus medullary bone. This set-up couldn’t have been cheap! I also had fun with a set of telescopes aimed at certain parts of the dinosaur skeletons, such as a series of fused vertebrae in the Galaemopus tail. These are outfitted with targeting lasers (!) to help pinpoint the key features.

Each “closer look” station includes a telescope (with targeting laser!) aimed at an important skeletal feature, plus a bronze cast of that same element.

This bronze miniature Allosaurus is one of four similar models.

Not every visitor can see the fossil mounts, so CMC worked with David Grimes of the Clovernook Center for the Blind and Visually Impaired to help people with low vision experience the exhibit. Braille is incorporated into many of the displays, and the hall is full of touchable bronze models, ranging from individual bones (like the aforementioned Galaemopus vertebrae) to fleshed-out reconstructions (such as Confuciusornis). Four of the dinosaur mounts are recreated as bronze miniatures. Structures like ribs and vertebral processes are quite thin at this scale and susceptible to bending or breaking, so the exhibit team went with a half-fleshed look to make the models more durable. The Field Museum landed on the same solution with the touchable miniature SUE, but credit is due to the CMC team for getting their models to stand up, rather than being presented in relief.

A real Apatosaurus skull, one of many treasures hidden away in smaller cases throughout the hall.

If I were to critique one element of the hall, it would be that some of the labels, graphics, and interactives are spatially disconnected from the fossils they relate to. For example, a digital touchscreen where visitors can manipulate a 3D scan of an Apatosaurus skull is nowhere near the real skull displayed elsewhere in the exhibit, and the only label for Othnielosaurus is on the opposite side of the platform from the mounted skeleton. This is, of course, a minor concern, and I can only imagine the difficulty of arranging an exhibit with as much verticality as this one.

Overall, the new CMC dinosaur hall is fantastic, whether one is considering the specimens on display, the story being told, or the aesthetics of the space. The collection of real, new-to-science specimens makes this exhibit stand out among other paleontology halls, but I’m curious how the museum’s general audience will respond. A once-expansive museum closed for two years, and opened with an excellent exhibit that nevertheless is much smaller than what was once on display. Will visitors be satisfied with quality over quantity? And will they keep returning as new CMC exhibits are completed over the coming years? Time will tell.

The fossils in question were discovered by Barnum Brown in 1914 during an American Museum of Natural History expedition to Alberta. It was the largest but least complete of several (presumed) Gorgosaurus skeletons collected by Brown, and only the skull was ever displayed in New York. In 1955, Field Museum trustee Louis Ware bought the fossils, an event heralded in the members’ newsletter as “the most important acquisition to the museum in recent years.” Preparator Orville Gilpin assembled the skeleton with the help of Stanley Kukzek, Cameron Gifford, and William Turnbull. Gorgeous George debuted in the Field Museum’s central Stanley Field Hall in March 1956, alongside a scale model created by staff artist Maide Weibe.

The similarities to modern mounting techniques on display in the video are more striking than the differences. From ratchets to chain hoists, the tools used by Gilpin and his colleagues appear quite similar to those used for this sort of work today. I suppose the lab coat-over-slacks look has gone out of style, though.

Gorgeous Gorge in its updated poses, as it is exhibited today. Photo by the author.

Gorgeous George remained in place until 1990, when it was relocated and remounted as part of the Life Over Time exhibition. While the updated Daspletosaurus trades the old Godzilla pose for a more accurate horizontal posture, it does not include the original skull (as Gilpin’s version did). The real skull is now on display at the Museum’s east entrance, however.

When the fossil halls at the National Museum of Natural History closed for renovation in 2014, five years seemed like an interminable amount of time to wait for the reopening. But the NMNH crew has been hard at work, and suddenly the June 2019 debut of the new National Fossil Hall is almost in sight. I’ve mostly avoided reporting on each and every bit of information pertaining to the new exhibit, but as we approach the one-year-to-opening milestone the drip is likely to become a deluge. That means that this is probably a good time to do a round-up of everything that has been officially revealed about the new exhibit up to this point.

The East Wing Restored

The building that is now NMNH opened in 1910. Its granite-heavy, Beaux Arts construction was a departure from the Victorian style of the first United States National Museum, but it looked right at home with the other federal buildings around the National Mall. As originally designed, the building resembled a squat “T” from above, with three large wings (facing east, north, and west) extending from a central rotunda. The east wing — a vast space with bay windows, intricate plaster detailing, and a skylight three stories up — has always housed fossil displays. Over the course of the 20th century, however, the once spacious hall was repeatedly carved into smaller sections. Windows and architectural flourishes were covered up, and by the time the last round of renovations was completed in 1985 the east wing had become cramped and gloomy.

A Story of Environmental Change

Many exhibits and books about paleontology portray the evolution of life as though it occurred in a vacuum. In fact, the evolution of animals and plants is primarily driven by environmental upheaval — changing climate, shifting geography, and so forth. Sometimes this relationship goes the other way, and keystone organisms (such as grass in the Neogene or humans in the present day) drastically change the world around them. Environmental change over time is at the heart of the National Fossil Hall’s story. It’s worth quoting the official theme statement in full:

Visitors to the Museum will be able to explore how life, environments, and ecosystems have interacted to form and change our planet over billions of years. By discovering and harnessing the tools and methods paleobiologists use to study fossils, visitors will gain a deeper understanding of how the world works.

The distant past affects all of us today and will continue to do so in the future. How will climate change impact the natural world and our daily lives? How can we make informed choices about our ecosystems as individuals and as a species? How can we all become informed citizens of a changing planet?

These themes are reflected by the physical layout of the exhibit, which is chronological but not strictly proportional. Specimens are clustered onto islands situated throughout the open floorplan, each representing North America at a particular point in time. While anchored by a few charismatic mounts, the islands also include all manner of small animals, invertebrates, and plants that were part of that environment. In this way, each island shows a complete ecosystem that existed at a particular time. Moving among these displays, visitors should get a sense of how phenomena like climate change and faunal interchange can completely transform an ecosystem over millions of years.

During the development process, curators and exhibit specialists agreed that the hall should not be an encyclopedia of past life. Instead, everything ties back to main story. Big, showy specimens like dinosaurs are contextualized as products of environmental change. Meanwhile, fossils that visitors might otherwise overlook but are critical to our understanding of ecological change over time, like pollen grains or leaves, are literally and figuratively pedestaled to emphasize their importance.

The Nation’s T. rex

The Nation’s T. rex, temporarily assembled in the Research Casting International workshop. Image by Great Big Story.

The centerpiece of the National Fossil Hall is a real Tyrannosaurus rex skeleton — the first real T. rex (as opposed to a cast) the Smithsonian has ever displayed. The specimen in question has been known as the “Wankel Rex” since it was discovered by avocational fossil hunter Kathy Wankel in 1988. It has been held in trust at Bozeman, Montana’s Museum of the Rockies, but since it came from Army Corps of Engineers land it is technically owned by the U.S. federal government. Although several casts of the Wankel Rex are on display around the world, the original fossils have never before been assembled into a standing mount. That’s changing now that the fossils have been transferred to the Smithsonian.

Curator Matt Carrano designed a deliriously cool pose, with the Tyrannosaurus poised as though prying the head off of a prone Triceratops. NMNH is visited by eight million people every year, so the Wankel Rex (now the Nation’s T. rex) will soon be the most viewed T. rex skeleton in the world. The Nation’s T. rex story has been covered by the Washington Post, NPR, National Geographic, and Smithsonian Magazine, among many others.

Poses that Show Behavior

The remounted mammoth demonstrates plausible behavior. Left image by the author, right image from Smithsonian Magazine.

Historically, mounted fossil skeletons were most often given anatomically neutral poses. This was a structural engineering necessity as much as it was a curatorial preference. However, modern technology has made it possible to safely display casts and even real skeletons in surprisingly dynamic poses. At many museums, this has usually manifested as mounted skeletons fighting or simply roaring at each other. In contrast, the NMNH team has endeavored to create dynamic mounts that show a greater variety of interesting behavior evidenced by the fossil record. For example, the remounted mammoth (shared during a talk by NMNH Director Kirk Johnson) is pushing its tusks along the ground, as if clearing snow off the grass. The Allosaurus (headless in the right image) is crouching next to a nest mound. Even the aforementioned T. rex and Triceratops scene is inspired by real research into T. rex feeding mechanics.

The Anthropocene

Most exhibits about the history of life close at some point in the past, but the National Fossil Hall continues the story into the present day. We are in the midst of an extinction event of our own making, and anthropogenic climate change, habitat destruction, and invasive species are as dangerous as any asteroid. During our very limited time on Earth, humans have altered the climate, the rate of erosion, and the acidity of oceans. Whether or not you think adopting “Anthropocene” as a formal geologic unit is reasonable, we have inarguably changed the planet in geologically measurable ways.

Curator Scott Wing discussed his approach to interpreting the age of humans in a Geological Society of America talk and in an Earth Matters blog post. The key is to make it clear that in spite of our destructive potential, humans have the power to mitigate and manage the consequences of altering the world around us. The exhibit will show visitors how they can take responsibility for humanity’s collective legacy.

Marsh Dinosaurs Re-imagined

The new Edmontosaurus cast replaces the original mount, which had gone unmodified since 1904. Images by NMNH Paleobiology and Will S.

Most of the dinosaur skeletons exhibited at NMNH were assembled before 1920. Originally excavated by O.C. Marsh’s crews in the 19th century, these specimens have gone on to lead second lives on display, and have been seen by generations of visitors. Nevertheless, time has taken its toll. Some mounts have been rendered out-of-date by new discoveries, while others have gradually deteriorated due to fluctuating temperature and humidity, not to mention constant vibration from passing crowds. Before the fossil halls closed in 2014, NMNH preparators had already dismantled three historic dinosaurs (Triceratops, Stegosaurus, and Camptosaurus) and replaced them with updated casts. Returning these fossils to the collections ensures their continued safety, while also giving paleontologists a chance to study them for the first time in decades.

The renovation has been an opportunity to give other at-risk specimens the same treatment. It was especially important to get the real Ceratosaurus, Edmontosaurus, and Thescelosaurus skeletons off the exhibit floor because these are all holotypes — the original specimens that were used to define the species. Set in plaster on the exhibit walls, these important skeletons were virtually inaccessible. And as the preparators discovered when they removed them, they had not even been fully extracted from the rock they were found in. The real fossils are now available for research, while casts with lively poses and up-to-date anatomy will take their place on display (before anyone panics, the new exhibit will still feature several real dinosaur skeletons).

The Pocahontas Mine

As reported by the Bluefield Daily Telegraph, a Smithsonian crew of paleobotanists, geologists, and exhibits specialists visited the historic Pocahontas Exhibition Mine last November. This coal mine near Pocahontas, Virginia operated from 1882 to 1938, when ceased production and became a tourist attraction. The Smithsonian crew took photographs, video, and silicon molds of the mine’s walls, which are covered with Carboniferous-era plant impressions. A reconstruction of the fossiliferous mine will anchor the Carboniferous section of the exhibit.

Treasures from the Collection

A typical natural history museum has less than one percent of its collection on display at any time, and NMNH is no exception. In addition to introducing brand-new specimens and updating old ones, the renovation is an opportunity to bring a variety of never-before-displayed objects from the collections to the display floor. Of the hundreds of specimens earmarked for display, I can only highlight a few. There’s the historic cast of the plesiosaur Rhomaleosaurus, which has been in the collection since 1895 but never displayed. There’s the skull of the tusked whale Odobenocetops, which preparator Michelle Pinsdorf profiled in a webcast last year. Carrano showed NPR’s Adam Cole a sauropod osteoderm, collected decades ago but only identified recently. And then there’s the near-perfect Ophiacodon pictured above, collected in 1988 by Arnie Lewis and Nicholas Hotton. I remember this guy from my intern days, when it was referred to as “sleeping beauty.”

Research Casting International will start installing the large skeletons this summer, and then the countdown to opening day begins in earnest. Here’s wishing the NMNH team all the best as their years of work finally comes to fruition!

Paleoartist Tyler Keillor has not one but two new tyrannosaur sculptures on display in museums north of Chicago, and this past weekend I paid both of them a visit. Keillor has been reconstructing extinct animals since 2001, most frequently in collaboration with Paul Sereno. You may well have seen Keillor’s fleshed models of Rugops, Kaprosuchus, Eodromaeus, and others, all commissioned by Sereno to accompany press releases announcing new discoveries. Keillor also specializes in restoring incomplete fossil material, assembling physical or digital models of the complete, undamaged bones. The composite Spinosaurus skeleton from the 2014 National Geographic traveling exhibit was his work, as is the skull on the mounted skeleton of Jane the juvenile Tyrannosaurus at the Burpee Museum of Natural History.

Tyler Keillor’s Dryptosaurus at the Bess Bower Dunn Museum.

One of Keillor’s latest and most ambitious pieces debuted on March 24th at the brand-new Bess Bower Dunn Museum in Libertyville, Illinois. Standing at the entrance to the museum’s galleries, the life-sized Dryptosaurus is a show-stopping centerpiece. Never mind that no dinosaur fossils have been found in Illinois – Dryptosaurus lived on the other side of the Cretaceous continent of Appalachia, which is as good an excuse as any to include a giant model dinosaur.

During the very well-attended opening event, Keillor gave a standing-room-only talk about creating the model. Dryptosaurus is only known from a handful of fossils, the most complete parts being the arm and leg. Working with Richard Kissel, who served as the project’s scientific advisor, Keillor had to make a number of educated choices to turn the available fossil material into a 20-foot fleshed model. The shape of the head, for example, is based on that of Jane, while the tiny, millimeter-sized scales are informed by recently published skin impressions of various tyrannosaurs. Less certain is the choice to give Dryptosaurus a two-fingered hand. For the time being, the three-fingered skeletons Research Casting International built for the New Jersey State Museum are no less reasonable.

Opening day at the Dunn Museum was mobbed – it’s great to see so many people excited about a new museum!

Keillor’s 2009 Dryptosaurus head is meant to be a male, while the new sculpture represents a female.

During the planning stages, Keillor prepared three possible poses for the museum to pick from. The Dryptosaurus could be standing tall, leaning forward with its mouth open, or crouching down next to a nest mound. Keillor favored the nesting pose, both because it was unusual and because the Dryptosaurus holotype fossils may have come from an animal that had recently laid eggs*. Unsurprisingly, museum staff opted for the more spectacular open-mouthed version.

The bulk of the model is foam, created on a milling machine using data from a digital model produced by Keillor. The foam body form is covered with nearly 200 pounds of epoxy putty, applied and textured by hand. Keillor casted the head as a separate piece, using the molds from a standalone Dryptosaurus head he produced for the Dunn Museum’s predecessor in 2009. The patches of fluff are made from a commercially-available synthetic fiber that resembles kiwi feathers.

*Edward Cope noted in the 1880s that the Dryptosaurus limb bones had large, hollow medullary cavities. Gravid female birds grow extra layers of bone in their medullary cavities to stockpile calcium, which they use to produce eggshells. We now know that several non-avian dinosaur species did the same.

Little Clint at the Dinosaur Discovery Museum.

Keillor’s other new model is “Little Clint” the infant Tyrannosaurus rex, which debuted at the Dinosaur Discovery Museum in Kenosha, Wisconsin with absolutely no fanfare. The model is part of a new exhibit all about the discovery and interpretation of the pocket-sized T. rex fossils it’s based on. Frustratingly, there’s no mention of the exhibit on the museum’s website, and I would have never known about it if Keillor hadn’t mentioned it (I’m sure it’s not the museum’s fault, I too have known the joys of working within the constraints of a large municipal website). The model is roughly two and a half feet long, and is almost grotesque in its spindly proportions. Judging by photos accompanying the model, Keillor used a traditional build-up process, rather than the physical-digital hybrid techniques employed in the making of the Dryptosaurus.

Dryptosaurus and Tyrannosaurus both belong to the same group of theropod dinosaurs (tyrannosaurs), but in creating the two models Keillor went in two very different directions when reconstructing their soft tissues. Working with Richard Kissel of the Yale Peabody Museum, Keillor gave Dryptosaurus a patchy coat of shaggy integument, as well as fleshy lips that would easily cover the animal’s teeth if it were to ever close its mouth. However, Carthage College’s Thomas Carr, scientific advisor for Little Clint, requested a scaly hide with a crocodilian tooth-exposing grin.

Little Clint’s toothy grin.

It turns out feathers and lips on large theropods (and tyrannosaurs in particular) are fairly contentious subjects, at least among the sort of people who like to argue about these things on the internet. It is well-established that feathery integument was widespread among theropods, and even certain other dinosaurs. Several members of the tyrannosaur family have been found with fossilized fuzz impressions, including the Dryptosaurus-sized Yutyrannus. This means it’s reasonable to expect that all tyrannosaurs, including Tyrannosaurus rex, were feathered to some degree. However, a recent publication by Phil Bell and colleagues suggests the opposite: an assortment of small skin impressions from Tyrannosaurus and its closest relatives reveal only scaly skin. Meanwhile, ongoing research by Robert Reisz demonstrates that theropods had fleshy lips, but this is contradicted by Carr’s own findings that some tyrannosaurs had armored scales on their maxillary margins.

So which interpretation of tyrannosaur soft tissue is right? For now, there is compelling evidence for both interpretations. Perhaps more fossils or new analytical techniques will eventually steer the consensus in one direction or the other. Or maybe we will never know for sure what the faces of Dryptosaurus and Tyrannosaurus looked like. For now, Keillor’s models make fascinating companion pieces. They are windows into two possible versions of the deep past, reminding us to accept a little ambiguity now and then.

Acrocanthosaurus at the North Carolina Museum of Natural Science. Photo by the author.

Following yesterday’s travelogue about the North Carolina Museum of Natural Science (NCSM), I thought I’d go into a little more depth about the museum’s star fossil. One of only five Acrocanthosaurus specimens ever found, NCSM 14345 is the most complete and the only one on public display. The mounted skeleton has been at the Raleigh museum since 2000. Among other things, its story highlights the challenging relationship between academic paleontologists and the private fossil trade.

Despite its current home in North Carolina, this Acrocanthosaurus hails from the town of Idabel in southeast Oklahoma, more than a thousand miles away. Avocational fossil hunters Cephis Hall and Sid Love (both now deceased) discovered the skeleton in 1983. After making an arrangement with the landowner, the pair spent the next three years carefully excavating the find.

The Acrocanthosaurus was recovered from the early to mid Cretaceous rocks of the Antlers Formation. Found in a deposit of fine sandstone and dark mudstone alongside lots of lignitized wood, the animal’s final resting place was probably a stagnant swamp or pond. Additional evidence for the depositional environment comes from the way the bones are preserved. They contain a great deal of pyrite, and were encrusted with dense concretions of calcium carbonate. Both of these minerals are formed by bacteria blooms in low-oxygen locales, such as the mud at the bottom of a swamp. Gouges in the skull, ribs, and foot indicate scavengers – crocodiles and possibly other Acrocanthosaurus – were feeding on the carcass before it was buried.

All told, the find included a complete skull (the only one of its kind), the pelvis and sacral vertebrae, both arms and shoulder girdles, the right leg, and parts of the rib cage and tail. Paleontologist Richard Cifelli of the Sam Noble Museum in Norman, Oklahoma became aware of the discovery in 1987. Cifelli initially hoped that the museum could acquire the specimen for study and safekeeping, but Hall and Love’s asking price was beyond their means. Instead, Hall and Love loaned the fossils to the University of Texas. They were unsatisfied with this arrangement, however, and drove down to Austin to retrieve their dinosaur (the details of this event are apparently contentious). Hall and Love then sold the fossils to Geological Enterprises, a for-profit outfit based in Ardmore, Oklahoma, for $225,000 plus the promise of a cast once the prep work was completed. Geological Enterprises founder A. Allen Graffham gave the specimen the nickname “Fran,” after his wife.

The meticulously reconstructed Acrocanthosaurus skull. Photo by the author.

The calcium carbonate concretions and heavy pyrite content made the Acrocanthosaurus a particularly challenging fossil to prepare. The concretions are like natural cement and are very difficult to remove without damaging the bones. Meanwhile, pyrite breaks down into sulfur when exposed to oxygen and humidity, which can cause bones to crumble. In 1991, Graffham outsourced the preparation job to the Black Hills Institute in Hill City, South Dakota. Terry Wentz led the preparation project at BHI, which was reportedly one of the most challenging assignments of his career. The concretions encrusting the bones were so dense that they often had to be ground off, rather than chipped. This process could take several hours just to remove a few millimeters of calcium carbonate. To make matters worse, removing pyrite releases acidic particulates into the air. Preparators had to wear respirators and the bones had to be prepared in vacuum boxes.

The most daunting part of the project was reconstructing the specimen’s beautiful and intact skull. Although virtually complete, the skull was found crushed flat. Everyone involved agreed that the skull would be more informative and more impressive if it could be reinflated, but that was easier said then done. Over a year of work went into carefully separating the individual skull bones and reassembling them into their life position.

After five years of what was probably one of the most difficult fossil prep jobs ever attempted, the Acrocanthosaurus was ready to be sold. However, Graffham initially had trouble finding a buyer. There were interested parties in Japan, but he reportedly did not want the fossils to leave the United States.

On October 4, 1997, another well-preserved theropod skeleton went up for auction at Sotheby’s in New York. Sue – the most complete Tyrannosaurus ever found – was already legendary thanks to the protracted legal battle over the fossils. Now that the one-of-a-kind skeleton was being sold at a high profile auction, paleontologists feared that it would disappear into the hands of a private collector. On the night of the auction, most of the museums and other public repositories in the running were outbid within minutes. The North Carolina Museum of Natural Science appeared to be the only museum left after the price topped $5 million, and so the hopes of the paleontological community rested on their shoulders. NCSM dropped out at $7.2 million, and moments later Richard Gray, a veteran of art auctions, won Sue on behalf of a mysterious client. Happily, that client turned out to be the Field Museum (with financial backing from McDonald’s and Disney), and so Sue ended up in a public repository after all.

The Acrocanthosaurus and its sauropod companion can be seen from the ground and from a balcony. Photo by the author.

Still, NCSM had been willing to stake an enormous amount of money on a name brand dinosaur, and they weren’t about to give up. Two months after the Sue auction, the Friends of the North Carolina Museum of Natural Sciences bought the Acrocanthosaurus from Graffham’s company for $3 million. BHI prepared the mount, which debuted along with the rest of the museum’s new building on April 7, 2000. It may not be coincidental that this was just one month before the mounted skeleton of Sue was unveiled in Chicago.

The Acrocanthosaurus occupies a well-lit, circular atrium on the museum’s third floor. Visible both from the ground and from a balcony, the mount is accompanied by a rather goofy-looking sauropod statue. Model pterosaurs circle overhead on a rotating arm, and recreations of theropod and sauropod tracks from Dinosaur State Park in Paluxy, Texas can be seen throughout the room. The original skull is on display in a case outside the atrium.

Sadly, pyrite deterioration has continued to ravage the delicate fossils. Several of the original bones once included in the NCSM mount have been retired to the collections for safekeeping. As of this year, only the arms, right foot, and vertebrae appear to be original material. The rest have been replaced with casts.

Exhibit signs have also changed since the 2000 debut. NCSM exhibits staff learned from surveys that 80% of visitors thought the dinosaur on display was a T. rex, and plenty more assumed the whole skeleton was a replica. In response, most of the signage was redesigned. The displays now highlight the differences between “Acro” and T. rex, and highlight the exceptional rarity of the museum’s Acrocanthosaurus specimen.

A number of NCSM 14345 casts are on display at museums throughout North America, including the Virginia Museum of Natural History, the Houston Museum of Nature and Science, and the Kenosha Public Museum. As promised, Hall and Love were awarded a complete cast of the skeleton, but without the means to assemble or display it, the replica sat in storage for several years. Eventually, local third and fourth graders successfully raised the $150,000 needed to display the cast at the Museum of the Red River in Idabel.

Acrocanthosaurus cast at the Virginia Museum of Natural History. Photo by the author.

Acrocanthosaurus cast at the Houston Museum of Nature and Science. Photo by the author.

Fossils are precious remains of real organisms, clues about ecosystems from long ago and the making of the world as we know it today. In an ideal world, all significant fossils would, from the moment of their discovery, be accessioned and held in a public collection at a museum or university. A fossil sitting on somebody’s mantelpiece or waiting to be sold at auction is doing nothing to grow our collective knowledge. However, public institutions don’t have the resources to find and excavate every fossil, and in the United States fossils found on private land belong to the landowners. That means that, for better or worse, there is a thriving commercial market for rare fossils.

A plurality of paleontologists do not engage with fossil dealers for ethical reasons. Indeed, even if they wanted to buy rare specimens, academic institutions can seldom match the prices individual collectors are willing to pay. Museums don’t usually have $3 million sitting around. That kind of money could fund a whole research team for years. As such, we’re left with a Catch-22. Paleontologists want important fossils to be in museums where they can be seen and studied by everyone. But if those fossils are in private hands, buying them would support and legitimize the industry that is also keeping fossils out of public collections. If there was an easy solution, it would have been worked out by now.

Nevertheless, serendipity occasionally strikes. This seems to have been the case with the Acrocanthosaurus. News about Sue generated interest in buying a name-brand dinosaur, and donors were willing to put up the money to get the specimen for NCSM. The skeleton is now in a public collection, at a free museum, no less. Meanwhile, the collectors were well compensated for their considerable investment. It’s hard to chalk that up as anything but a win, all around.

Eddy, D.R. and Clarke, J.A. 2011. New Information on the Cranial Anatomy of Acrocanthosaurus atokensis and Its Implications for the Phylogeny of Allosauroidea (Dinosauria: Theropoda). PLoS ONE 6:3:e17932.

In April 2014, the paleontology exhibits at the National Museum of Natural History closed for a wall-to-wall renovation. The re-imagined National Fossil Hall will reopen in 2019. We are now approaching the halfway point of this journey, which seems like a fine time to say farewell to some of the more charismatic specimens that are being rotated off display.

In comparison to the old exhibit, the new version will be influenced by a less-is-more design philosophy. While there will not be quite as many individual specimens on display, those that are included will be more visible and will be explored in more detail. This combined with the significant number of new specimens being added means that many old mainstays had to be cut from the roster. Cuts occur for a variety of reasons, including eliminating redundancy, preserving specimens that were not faring well in the open-air exhibit space, and making specimens that have been behind glass for decades available to a new generation of researchers. Retired specimens are of course not going far – they have been relocated to the collections where students and scientists can study them as needed.

Stegomastodon (USNM 10707)

The Stegomastodon in 2014. Photo by the author.

The young male Stegomastodon is the largest single specimen that is being retired from the NMNH fossil halls. James Gidley and Kirk Bryan collected this skeleton in the San Pedro Valley of Arizona, during the same 1921 collecting trip that produced the museum’s Glyptotherium (which will be returning). While the genus Stegomastodon was erected in 1912, Gidley referred his specimen to a new species, S. arizonae, due to its more “progressive” physiology and slightly younger age. By 1925, the skeleton was mounted and on display in the Hall of Extinct Monsters. While the original mount used the real fossil tusks, these were eventually replaced with facsimiles.

There are at least two reasons the Stegomastodon will not be returning in 2019. First, there are already two big elephants on display: the mammoth and the mastodon. Elephants take up a lot of space, and a third proboscidean offers diminishing returns when compared to the amount of floor space it requires. More importantly, the Stegomastodon is a holotype specimen, and the exhibit team elected to remove most of these important specimens from the public halls. This is both to keep them safe from the damaging effects of vibration, humidity, and fluctuating temperature, as well as to make them more accessible to researchers.

Paramylodon (USNM V 15164)

During the 1960s, Assistant Curator Clayton Ray oversaw the construction of the short-lived Quaternary Hall, which was reworked into the Hall of Ice Age Mammals. This meant creating a number of brand-new mounts, including several animals from the Rancho La Brea Formation in Los Angeles County. La Brea fossils are not found articulated, but as a jumble of individual elements preserved in asphalt. The Los Angeles Natural History Museum provided NMNH with an assortment of these bones, which preparator Leroy Glenn assembled into two dire wolves, a saber-toothed cat, and the sheep cow-sized sloth Paramylodon.

Zygorhiza (USNM PAL 537887)

When the Life in the Ancient Seas gallery opened in 1990, it featured a historic Basilosaurus skeleton that had been on display since the 1890s. This ancestral whale was relocated to the Ocean Hall in 2008, and a cast of the smaller whale Zygorhiza took its place in Life in the Ancient Seas. Since there is now an extensive whale evolution exhibit in Ocean Hall, this subject will not be a major part of the new paleontology exhibit. Both Zygorhiza and the dolphin Eurhinodelphis will have to go.

Tapirs, Horses, and Oreodonts

The tapir Hyrachyus and the mini-horse Orohippus. Photo by the author.

The last two major renovations of the NMNH fossil exhibits occurred when mammal specialists were in charge of the Paleobiology Department, and as a result the halls ended up with a lot of Cenozoic mammal mounts (at least 50, by my count). Virtually every major group was covered, often several times over. This menagerie has been culled for the new hall, which will focus on specimens that best tell the story of Earth’s changing climate during the past 66 million years. Casualties include the trio of Hagerman’s horses, the smaller horse Orohippus, the tapirs Hyrachyus and Helaletes, the ruminant Hypertragulus, and the oreodont Merycoidodon. Interestingly, the classic hall’s three large rhinos are sticking around, and will in fact be joined by at least one more.

Brachyceratops (USNM 7953)

Brachyceratops/Rubeosaurus. Photo by NMNH Department of Paleobiology.

The pocket-sized ceratopsian historically called Brachyceratops has been on display at NMNH since 1922. Discovered in 1913 by Curator of Fossil Reptiles Charles Gilmore, this animalis one of only a few dinosaur species excavated, prepared, described, and exhibited entirely in-house at NMNH. Assembled by Norman Boss, the mount is actually a composite of five individuals Gilmore found together in northeast Montana.

Gilmore described Brachyceratops as an unusually small but full-grown ceratopsian, but in 1997 Scott Sampson and colleagues confirmed that all five specimens were juveniles. Unfortunately, the fossils lack many diagnostic features that could link them to an adult form. According to Andrew McDonald, the most likely candidate is Rubeosaurus. Nevertheless, without the ability to recognize other growth stages of the same species, the name Brachyceratops is unusable and is generally regarded as a nomen dubium.

It is not difficult to surmise why the Brachyceratops would end up near the bottom of the list of specimens for the new exhibit. It is not especially large or impressive, it doesn’t have a recognizable name (or any proper name at all, really) and it doesn’t tell a critical story about evolution or deep time. With limited space available and new specimens being prepped for display, little Brachyceratops will have to go.

Corythosaurus (USNM V 15493)

Corythosaurus as seen in the 1960s. Photo courtesy of the Smithsonian Institution Archives.

In 1910, Barnum Brown of the American Museum of Natural History launched the first of several expeditions to the Red Deer River region of Alberta. Seeing Brown’s success and under pressure to prevent the Americans from hauling away so much of their natural heritage, the Canadian Geological Survey assembled their own team of fossil collectors in 1912. This group was headed by independent fossil hunter Charles Sternberg, who was accompanied by his sons George, Levi, and Charles Jr. Having secured several articulated and nearly complete dinosaur skeletons, Brown’s team moved on five years later. The Sternbergs, however, remained at the Red Deer River, and continued to collect specimens for the Royal Ontario Museum.

In 1933, Levi discovered a well-preserved back end of a Corythosaurus, complete with impressions of its pebbly skin. The Smithsonian purchased this specimen in 1937 for use at the Texas Centennial Exposition. It eventually found its way into the permanent paleontology exhibit at NMNH. Unfortunately, the half-Corythosaurus ended up crowded behind more eye-catching displays and was often overlooked by visitors. In the new exhibit, it will have to move aside to make room for new Cretaceous dinosaurs.

Assorted Dinosaur Skulls

Original skull of Hatcher the Triceratops, one of many dinosaur skulls coming off exhibit. Photo by the author.

In addition to complete dinosaur mounts, the old NMNH fossil halls included several dinosaur skulls, ranging from the giant cast of the AMNH Tyrannosaurus to the miniscule Bagaceratops. Most of these standalone skulls have been cut, although a few (Diplodocus, Camarasaurus, and Centrosaurus) are sticking around, to say nothing of new specimens being added. Other retirees in this category include the original skulls of Nedoceratops (labeled Diceratops), Triceratops, Edmontosaurus, and Corythosaurus, as well as casts of Protoceratops, Pachycephalosaurus, Stegoceras, Psittacosaurus, and Prenocephalae.

As usual, the reasons these specimens are coming off exhibit are varied. The Nedoceratops skull is a one-of-a-kind holotype that has been the subject of a great deal ofconflictingresearch over its identity and relevance to Maastrichtian ceratopsian diversity. Putting this specimen back in the hands of scientists should help clarify what this bizarre creature actually is. Meanwhile, many of the other skulls (e.g. Protoceratops, Psittacosaurus, and Prenocephalae) come from Asian taxa. In the new fossil hall, the Mesozoic displays will primarily focus on a few well-known ecosystems in North America.

Dolichorynchops (USNM PAL 419645)

Dolichorhynchops in the Life in the Ancient Seas exhibit. Photo by NMNH Department of Paleobiology.

The NMNH Dolichorhynchops is a relatively new mount. It was collected in Montana in 1977 and acquired in a trade with the Denver Museum of Nature and Science. Arnie Lewis prepared it for display in 1987. 24 years later, “Dolly” is being retired to the collections. This is not due to anything wrong with the specimen, but to make way for a bigger, cooler short-necked plesiosaur. NMNH purchased a cast of Rhomaleosaurus from the Henry Ward Natural Science Establishment in the 1890s, but it has not been on exhibit since at least 1910. This cast, which is based on an original at the National Museum of Ireland (and which is identical to the cast at the London Natural History Museum) will make its first public appearance in over a century in the new National Fossil Hall. Sorry, Dolichorhynchops.

This has hardly been a comprehensive list – just a few examples that illustrate the decisions that are made when planning a large-scale exhibit. If you are curious about other favorites from the old halls, you can check on their fate by searching the Department of Paleobiology’s online database. Just go to Search by Field and enter “Deep Time” under Collection Name to see most of the specimens earmarked for the new exhibit.

In December 1915, the American Museum of Natural History unveiled the very first mounted Tyrannosaurus rex skeleton, irrevocably cementing the image of the towering reptilian carnivore in the popular psyche. For a generation, AMNH was the only place in the world where one could see T. rex in person. Despite the tyrant king’s fame, old books emphasize the rarity of its fossils. The situation is very different today. In the last 30 years, the number of known Tyrannosaurus specimens has exploded. Once elusive, T. rex is now one of the best known meat-eating dinosaurs, and real and replica skeletons can be seen in museums around the world. The AMNH mount is no longer the only T. rex around, nor is it the biggest or most complete. It was, however, the first, and in a few weeks it will mark the 100th anniversary of its second life. Below is a partially recycled recap of this mount’s extraordinary journey.

AMNH 5027 in November 2015. Photo by the author.

The mount known as AMNH 5027 is actually a composite of material from two individuals. The first is the Tyrannosaurus rex holotype (originally AMNH 973, now CM 9380), which was discovered by Barnum Brown and Richard Lull during an AMNH expedition to Montana in 1902. The find consisted of little more than the pelvis, a single femur, one arm and shoulder, and fragmentary portions of the jaw and skull. Nevertheless, this was enough for AMNH director Henry Osborn to publish a brief description in 1905, as well as coin the species’ brilliantly evocative name. That same year, Adam Hermann prepared a plaster replica of the animal’s legs and pelvis, using Allosaurus fossils as reference when sculpting the missing lower legs and feet. This partial mount was initially displayed alongside the skeleton of a large ground bird, in order to accentuate the anatomical similarities.

Brown located a better Tyrannosaurus specimen in 1908. Apparently fearing poaching or scooping, Osborn wrote to Brown that he wished to “keep very quiet about this discovery, because I do not want to see a rush into the country where you are working.” After vanquishing many tons of horrific sandstone overburden, Brown returned to New York with what was at the time the most complete theropod specimen ever found. In addition to an “absolutely perfect” skull, the new find included most of the rib cage and spinal column, including the first half of the tail (Osborn 1916). Lowell Dingus would later describe this second specimen (the true AMNH 5027) as “a nasty old codger”, suffering from severe arthritis and possibly bone cancer. These pathologies were undoubtedly painful and probably debilitating.

Model of the unrealized T. rex showdown mount from Osborn 1913.

Osborn initially wanted to mount both Tyrannosaurus specimens facing off over a dead hadrosaur. He even commissioned E.S. Christman to sculpt wooden models which which to plan the scene (shown above). However, the structural limitations inherent to securing heavy fossils to a steel armature, as well as the inadequate amount of Tyrannosaurus fossils available, made such a sensational display impossible to achieve. Instead, the available fossils complemented one another remarkably well in the construction of a single mounted skeleton. Osborn noted this good fortune in 1916, but his statement that the two specimens were “exactly the same size” wasn’t quite accurate. The holotype is actually slightly larger and more robust than the 1908 specimen, and to this day the AMNH Tyrannosaurus mount has oversized legs.

The original Tyrannosaurus rex mount at AMNH. Note the original 1905 replica legs in the background. Photo from Dingus 1996.

Instead, Hermann’s team prepared a single Tyrannosaurus mount, combining the 1908 specimen with the reconstructed pelvis and legs based on the 1905 holotype. When the completed mount was unveiled in 1915, the media briefly lost their minds. In contemporary newspapers, the skeleton was called “the head of animal creation”, “the prize fighter of antiquity”, and “the absolute warlord of the earth”, among similarly hyperbolic proclamations. Even Osborn got in on the game, calling Tyrannosaurus “the most superb carnivorous mechanism among the terrestrial Vertebrata, in which raptorial destructive power and speed are combined.” With its tooth-laden jaws agape and a long, dragging lizard tail extending its length to over 40 feet, the Tyrannosaurus was akin to a mythical dragon, an impossible monster from a primordial world. This dragon, however, was real, albeit safely dead for 66 million years.

The AMNH’s claim to the world’s only mounted Tyrannosaurus skeleton ended in 1941, when the holotype was sold to the Carnegie Museum of Natural History. The Pittsburgh museum’s hunch-backed reconstruction of the tyrant king was on display within a year. Although no longer the only T. rex on display, the AMNH mount certainly remained the most viewed as the 20th century progressed. It became an immutable symbol for the institution, visited again and again by generations of museum goers. Its likeness was even used as the iconic cover art of Michael Crichton’s Jurassic Park.

By the 1980s, however, a new wave of dinosaur research had conclusively demonstrated that these animals had been active and socially sophisticated. The AMNH fossil galleries had not been updated since the 1960s, and the upright, tail-dragging T. rex in particular was painfully outdated. AMNH had once been the center of American paleontology, but now its displays were lagging far behind newer museums.

Restoration of AMNH 5027 was completed nearly three years before the hall reopened. Photo from Dingus 1996.

Between 1987 and 1995, Lowell Dingus coordinated a comprehensive, $44 million renovation of the AMNH fossil exhibits. As part of the project, chief preparator Jeanne Kelly led the restoration and remounting of the most iconic specimens, Apatosaurus and Tyrannosaurus. Of the two mounts, the Tyrannosaurus presented the bigger challenge. The fossils were especially fragile, and some elements, specifically the cervical vertebrae, had never been completely freed from the sandstone matrix. It took six people working for two months just to strip away the layers of shellac applied by the original preparators. All told, the team spent a year and a half dismantling, conserving, and rebuilding the T. rex.

Phil Fraley’s exhibit company constructed the new armature, which gave the tyrant king a more accurate horizontal posture. While the original mount was supported by obtrusive rods extending from the floor, the new version is actually suspended from the ceiling by a pair of barely-visible steel cables. Playing with Christman’s original wooden models, curators Gene Gaffney and Mark Norrell settled on a fairly conservative stalking pose, imbuing the mount with a level of dignity befitting this historic specimen. The restored AMNH 5027 was completed in 1992, but would not be unveiled to the public until the rest of the gallery was finished in 1995. Since that time, tens of millions of visitors have flocked to see this new interpretation of Tyrannosaurus. This is the skeleton that showed the world that dragons are real, and it is still holding court today.

References

Dingus, L. 1996. Next of Kin: Great Fossils at the American Museum of Natural History. New York, NY: Rizzoli International Publications, Inc.